Butter a metal cookie sheet and set aside.
In non-stick frypan, combine first set of ingredients. Bring to boil over medium-high heat. Stir until sugar is dissolved, about 2 minutes. Mixture will be bubbly and foamy looking BE CAREFUL THIS IS EXTREMELY HOT! Add pecan halves and stir while cooking for one and 1/2 minutes. Remove pecans to cookie sheet and spread to separate. Let cool thoroughly.
Whisk together dressing ingredients until combined. To assemble salad, toss greens with grapes, nuts and vinaigrette.